It was sent off with the intercepted letter, but did not reach Grouchy till after seven P.M. Domont soon after made the communication, that he had fallen in with the enemy in the direction of St.-Lambert; the Emperor might be assured that the troops he had seen were enemies, and that he had sent out patrols to find out Grouchy and to open a communication with him. Napoleon remarked to Soult, “This morning we had ninety chances for us; the arrival of Bulow loses us thirty, but we have still sixty against forty. If Grouchy repair the horrible fault which he committed yesterday in amusing himself at Gembloux, and send his detachment with rapidity, the victory will be more decisive, because Bulow’s corps will be quite destroyed.” The Emperor still felt sanguine as to the successful result of the battle, notwithstanding he had received no intelligence from Grouchy, nor any information which he considered satisfactory respecting the Prussians. It was only by a gross oversight on the part of Napoleon, or some of his officers, that Bulow was allowed to approach his right. Had he detached six or eight thousand men of all arms on the 17th, or at an early hour on the 18th, to command the entrance to the defiles of the Lasne and St.-Lambert, through which Bulow had to pass, and not above ten minutes’ gallop from the French right (consequently the force could have been recalled at any moment,) Napoleon could have kept Bulow’s corps, out of action until the arrival of Zieten’s (1st) corps, at about eight o’clock, and before that hour he might with his whole force have assailed Wellington’s position. The appearance of the Prussians at St.-Lambert was ominous for Napoleon: it compelled him to alter his plan of battle, and tended to paralyze part of his reserves. The Prussians were now in great force between Grouchy’s corps and the French right. Grouchy might indeed fall upon the Prussian rear; but he might also be retarded at the passage of the Dyle, or by some other difficulty or misfortune. The prospect was sufficiently gloomy to make Napoleon detach some cavalry for the purpose of observing Bulow’s corps, and to keep a strong force in hand ready to check the Prussians, should they attempt to disturb his right.